Zhuang Ye, Thompson Jeffrey S, Zygarlicke Christopher J, Pavlish John H
Energy & Environmental Research Center, University of North Dakota, Grand Forks, North Dakota 58202-9018, USA.
Environ Sci Technol. 2004 Nov 1;38(21):5803-8. doi: 10.1021/es030683t.
A bench-scale entrained-flow reactor was used to extract flue gas produced by burning a subbituminous Belle Ayr coal in a 580-MJ/h combustion system. The reactor was operated at 400 degrees, 275 degrees, and 150 degrees C with a flow rate corresponding to residence times of 0-7 s. Transformations of elemental mercury (Hg0) and total gas mercury (Hg(gas)) in the reactor were evaluated as functions of temperature and residence time. The most significant mercury transformations (Hg0 to Hg(p) and Hg0 to Hg2+) occurred at 150 degrees C, while virtually no obvious mercury transformations were observed at 275 degrees and 400 degrees C. Approximately 30% of total mercury has been oxidized at temperatures higher than 400 degrees C. A mass transfer-capacity limit model was developed to quantify in-flight mercury sorption on fly ash in flue gas at different temperatures. A more sophisticated model was developed to demonstrate not only the temperature and residence time effects but also to consider the effective surface area of fly ash and dependence of mercury vapor concentration on mercury transformations in flue gas. The reaction orders were 0.02 and 0.55 for Hg0 and Hg(gas), respectively. Only a few percent of the total surface area of the fly ash, in the range of 1%-3%, can effectively adsorb mercury vapor.
使用一个实验室规模的携带流反应器来提取在一个580兆焦/小时燃烧系统中燃烧次烟煤贝亚尔煤产生的烟道气。该反应器在400℃、275℃和150℃下运行，流速对应于0至7秒的停留时间。评估了反应器中元素汞（Hg0）和总气态汞（Hg(gas)）的转化情况，作为温度和停留时间的函数。最显著的汞转化（Hg0转化为Hg(p)和Hg0转化为Hg2+）发生在150℃，而在275℃和400℃几乎未观察到明显的汞转化。在高于400℃的温度下，约30%的总汞已被氧化。建立了一个传质容量极限模型，以量化不同温度下烟道气中飞灰上的飞行中汞吸附。开发了一个更复杂的模型，不仅展示温度和停留时间的影响，还考虑飞灰的有效表面积以及汞蒸气浓度对烟道气中汞转化的依赖性。Hg0和Hg(gas)的反应级数分别为0.02和0.55。飞灰总表面积中只有1% - 3%的一小部分能够有效地吸附汞蒸气。
